A Methodology for techno-economic comparison of PV inverter structure topologies :

Abstract

Sri Lanka’s recent energy policies are focused on promoting economically viable solar power generating schemes introducing novel market segments. It’s envisioned to ensure nation’s energy security while promoting utilization of indigenous energy generating resources. Recent 1 MWp solar power development scheme is one such novel market segment. PV inverters play a significant role in any PV plant performance. Lack of research on identifying the technically and economically most suited PV inverter architecture has caused high risk of failed project objectives. Following research presents a comprehensive framework for a techno-economic comparison of different PV inverter architectures which are central inverters, string inverters, micro inverters and power optimizer systems. 1 MWp capacity PV plant models are designed for analytical purposes of the research. Technical aspects such as energy yield, safety aspects, power output quality, reliability and performance monitoring are assessed using simulation tools (PVSyst, PSCAD and MATLAB), field data analysis, Cost Priority Number method and Markov reliability models. Economic impact is evaluated using Levelized Cost of Electricity calculations and project financial assessments followed by a sensitivity analysis. It’s found that distributed power electronics in PV systems provide higher energy yield, reduced safety risk, higher reliability and lower system down-time due to failures compared to central and string inverters. String inverters and power optimizer systems are more economically feasible in 1 MWp scale. Finally, it’s concluded that the presented methodology furnishes a proper techno-economic comparison for different PV inverter architectures.